VIRTUAL PRIVATE NETWORKS

. Why Build a Virtual Private Network?

Until now there has always been a clear division between public and private networks.
A public network, like the public telephone system and the Internet, is a large collection of
unrelated peers that exchange information more or less freely with each other. The people
with access to the public network may or may not have anything in common, and any given
person on that network may only communicate with a small fraction of his potential users.
A private network is composed of computers owned by a single organization that share
information specifically with each other. They're assured that they are going to be the only
ones using the network, and that information sent between them will (at worst) only be seen
by others in the group. The typical corporate Local Area Network (LAN) or Wide Area
Network (WAN) is an example of a private network. The line between a private and public
network has always been drawn at the gateway router, where a company will erect a firewall
to keep intruders from the public network out of their private network, or to keep their own
internal users from perusing the public network.